EP1061941A2 - A pharmaceutical composition containing ezrin mutated on tyrosine 353 - Google Patents

Abstract

The invention relates to a pharmaceutical composition containing an effective amount of ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof, in association with a pharmaceutically acceptable carrier, for use preferably in the prevention and/or treatment of tumors.

Description

A pharmaceutical composition containing ezrin mutated on tyrosine 353"

The present invention relates to a pharmaceutical composition containing ezrin mutated on tyrosine 353, for controlling cell survival and apoptosis and for use preferably in the prevention and/or treatment of tumors.

Ezrin was characterized as a component of brush-border and placental microvilli in the early 1980s (Bretscher et al., 1983). The family now consists of four members in vertebrates, namely ezrin, radixin, moesin (ERM proteins) and merlin (moesin-ezrin-radixin-like protein also named schwanπomin). The structure of all family members consists of an amino-terminal globular domain followed by an α-helical region and a carboxy-terminal domain. The family belongs to the band 4.1 superfamily on the basis of sequence homology of the amino-terminal domain with the erythrocyte membrane-cytoskeleton linker protein band 4.1 Ezrin, radixin and moesin are thought to work as cross-linkers between plasma membranes and actin-based cytoskeletons (Arpin et al., 1994)..

Phosphorylation may regulate the activity of the proteins triggered by several growth factors. ERM proteins could be regulated by phosphorylation of different protein domains, including Tyr145 located in the amino-terminal domain and Tyr353 in the α-helical domain. These two residues are phosphorylated by EGF receptor (Krieg et al. (1992)). Phosphorylation of a threonine residue in the carboxy-terminal domain may also regulate the actin- binding ability of ERM proteins (Vaheri et al., 1997, Tsukita et al., 1997). The authors of the present invention have recently shown that ezrin is an effector of hepatocyte growth factor-mediated migration and morphogenesis in epithelial cells (Crepaldi et al., 1997).

The authors of the present invention have now discovered that ezrin mutated on tyrosine 353 as shown on figure 1 impairs the ability of cells to survive in a collagen matrix, more particularly in a collagen type I matrix, and induces apoptosis, that is to say cell death. Such apoptosis could be due to a disruption of the signal transmission mediated by molecules of adhesion In vivo, normal cells lie on a basal membrane which does not contain collagen type I Tumor cells, and more particularly metastatic cells, may contact the extracellular matrix which contains collagen type I and are thus sensitive to the effect of ezrin mutated on tyrosine 353 Consequently ezrin mutated on tyrosine 353 is a good candidate for the prevention and/or treatment of tumors Furthermore, ezrin mutated on tyrosine 353 could be useful to prevent metastasis and/or to lead to the apoptosis of migrating tumor cells involved in metastasis

A subject of the present invention is thus a pharmaceutical composition containing an effective amount of ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof, in association with a pharmaceutically acceptable carrier A further subject of the present invention is a pharmaceutical composition containing an effective amount of DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding functional fragments or derivatives thereof in association with a pharmaceutically acceptable carrier

The pharmaceutical compositions of the invention are more particularly useful for the prevention and/or treatment of tumors, namely for the prevention and/or treatment of metastasis

The aminoacid sequence of native human ezrin is shown on figure 1 The expression "ezrin mutated on tyrosine 353" or "Y353 ezπn mutant" refers to a polypeptide having the sequence shown of figure 1 , except for the aminoacid 353 which is different from a tyrosine residue

The aminoacid 353 of the Y353 ezrin mutant may be preferably a phenylalanine residue, but may also be any other aminoacid residue which cannot be phosphorylated Said Y353 ezrin mutant may be produced from native ezrin by site-directed mutagenesis, which is a technique well-known in the art (Crepaldi et al , 1997) The term "functional derivative" is understood to refer to any polypeptide variant of Y353 mutant or any molecule resulting from a genetic and/or chemical modification of Y353 ezrin mutant, that is to say obtained by mutation, deletion, addition, substitution and/or chemical modification of a single or of a limited number of aminoacids, as well as any isoform sequence, that is to say a sequence which is identical to the Y353 ezπn mutant sequence, except for one or more aminoacids in the form of the D enantiomer, the said isoform, modified or variant sequences having conserved the biological activity of the Y353 ezπn mutant The biological activity of the Y353 ezrin mutant refers to the ability of Y353 ezrin mutant to induce apoptosis

More particularly the biological activity of the Y353 ezrin mutant refers to the property of the Y353 ezrin mutant to impair the ability of cells to survive in a collagen matrix, more particularly in a matrix containing collagen type I or to grow in aggregates in suspension This indicates that signalling from cell-cell and cell-substratum contacts is impaired

The term "derivatives" thus comprises any polypeptide having an aminoacid sequence which is substantially identical to the Y353 ezπn mutant in which one or more residues have been conservatively replaced by a functionally similar residue and which demonstrates its ability to mimic the Y353 ezrin mutant as described in the present invention Examples of conservative replacements include the replacement of a hydrophobic residue such as isoleucine, valine, leucine or methionine with another hydrophobic residue, the replacement of a polar residue such as arginine with lysine, glutamme with asparagine or glycine with seπne, the replacement of a basic residue such as lysine arginine or histidine with another basic residue or the replacement of an acidic residue such as aspartic acid and glutamic acid with another acidic residue Similarly, the term "derivatives" comprises any polypeptide having one or more residues which are derived chemically from Y353 ezrin mutant by reactⁱon of a functional group Such derived molecules include, for example, molecules in which the free ammo groups have been substituted in order to form amine hydrochloπdes The free carboxylic acid groups may be derived in order to form salts, methyl or ethyl esters or other types of esters or hydrazides The free hydroxyl groups may be substituted in order to form O-acyl or O-alkyl derivatives The imidazole nitrogen of the histidine may be substituted in order to form N-imidazole benzylhistidine Peptides which contain one or more derivatives of an ammo acid in its natural form from the 20 natural ammo acids are also included as chemical derivatives For example, pro ne may be replaced with 4-hydroxyprolιne, lysine may be replaced with 5-hydroxylysιne , histidine may be replaced with 3-methyl-hιstιdιne , serine may be replaced with homoseπne , and lysine may be replaced with ornithme

The term "functional fragment" is understood to refer to any polypeptide having an aminoacid sequence selected from any part of Y353 ezrin mutant sequence, and containing of course said aminoacid 353 Preferred fragments contain at least the aminoacid sequence between aminoacid 350 and aminoacid 356 as shown on figure 1

According to one embodiment of the invention polynucleotides are administered into a patient to achieve controlled expression of the Y353 ezrin mutant or fragments or derivatives thereof

Said polynucleotides are DNA or RNA sequences encoding the Y353 ezrin mutant or encoding fragments or derivatives thereof, operatively linked to the genetic elements necessary for their expression by a target cell, such as promoters and the like

Said polynucleotides can be administered in a "naked" form, i e free of any delivery vehicle that can act to facilitate entry into the cell

The DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding fragments or derivatives thereof, may be inserted into an expression vector, in which it is operatively linked to components which allow its expression to be regulated, in particular such as transcription promoters and/or terminators Such an expression vector may be in particular a plasmid, a phage or any type of recombinant virus

Among the prokaryotic transformation vectors which are well known to those skilled in the art, mention may be made of the ZAP Lambda phage vector and the pBluescπpt plasmid (Stratagene) Other vectors which are suitable for the transformation of E coll cells include pET expression vectors (Novagen) for example, pET11a, which contains the T7 promoter, the T7 terminator, the E coli mducible Lac operon and the Lac repressor gene , and pET 12a-c, which contains the T7 promoter, the T7 terminator and the E coli omPT secretion signal

The vectors which are particularly preferred for the transfection of mammalian cells are vectors containing the cytomegalovirus (CMV) promoters such as pcDNAI (Invitrogeπ), vectors containing the MMTV promoter such as pMAMNeo (Clontech) and pMSG (catalogue n° 27-4506-01 from Pharmacia) and vectors containing theSV40 promoter such as pSVβ (Clontech)

In the present invention, a promoter refers to a DNA segment which controls the transcription of DNA to which it is operatively linked The promoter region includes specific sequences which are sufficient for recognition of the RNA polymerases, for binding and the initiation of transcription In addition the promoter region includes sequences which modulates this recognition, and the initiation of the binding and of the transcription of the RNA polymerase activity As examples of promoters considered for use in the present invention, mention may be made of the SV40 promoter, the cytomegalovirus promoter, the mouse mammary tumour virus promoter (induced by steroids) and the Maloney muπne leukamia virus promoter

The polynucleotides encoding Y353 ezrin mutant or fragments or derivatives thereof can be also administered along with any material that promotes transfection, such as liposomal formulations, charged lipids such as Lipofectm™ or precipitating agents such as CaPO₄

The pharmaceutical compositions of the invention may be administered to any animal which may experience the beneficial effects of the compositions of the invention Foremost among such animals are humans, although the invention is not intended to be so limited.

DNA or RNA sequences encoding the Y353 ezrin mutant or encoding functional fragments or derivatives thereof can be administered to the patient by any method that delivers mjectable materials to cells of the patient, such as by injection into the interstitial space of tissues such as muscles or skin, introduction into the circulation or into body cavities or by inhalation or insufflation A naked polynucleotide is injected or otherwise delivered to the animal with a pharmaceutically acceptable liquid carrier For all applications, the liquid carrier is aqueous or partly aqueous, comprising sterile, pyrogen-free water The pH of the preparation is suitably adjusted and buffered

The pharmaceutical compositions of the present invention (containing an effective amount of ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof or containing an effective amount of DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding functional fragments or derivatives thereof), may be administered by any means that achieve the intended purpose For example, administration may be by parenteral, subcutaneous, intravenous, intradermal, intramuscular, intrapeπtoneal, or transdermal routes Alternatively, or concurrently, administration may be by the oral route The peptides and pharmaceutical compositions can be administered parenterally by bolus injection or by gradual perfusion over time

Ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof or DNA or RNA encoding ezrin mutated on tyrosine 353, or encoding functional fragments or derivatives thereof must be targeted toward tumor cells For that purpose, the pharmaceutical compositions of the invention can be administered by direct injection to tumor aggregates

Specific targeting to tumor cells may also be achieved by coupling Y353 ezrin mutant peptide with an antibody which specifically recognizes tumor cells Y353 ezrin mutant peptide may also be delivered to tumor cells by liposomes carrying antibodies specific for tumor cells The dosage administered will be dependent upon the age, sex, health and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired.

The dose ranges for the administration of the composition of the present invention are those large enough to produce the desired effect. The doses should not be so large as to cause adverse side effects.

Preferred doses of the Y353 ezrin mutant peptide for humans range between about 10^"9-10^"3 moles for one intratumoral injection. Injections are performed as necessary, the rate and amount being determined by the practioner.

In addition to the Y353 ezrin mutant and its derivatives which themselves are pharmacologically active, pharmaceutical compositions may contain suitable pharmaceutically acceptable carriers comprising excipients and auxiliaries which facilitate processing of the active compounds into preparations which can be used pharmaceutically.

To enhance delivery or bioactivity, the peptides (Y353 ezrin mutant and its derivatives) can be incorporated into liposomes using methods and compounds known in the art.

A further subject of the present invention is a method for the prevention and/or treatment of tumors, more particularly for the prevention and/or treatment of metastasis, comprising the administration to a patient in need of such treatment of an effective amount of a pharmaceutical composition according to the present invention.

All kinds of tumors are comprised. Tumors which are very likely to lead to metastasis are preferably aimed at. Examples of such tumors include epithelial cell tumors such as melanoma, and carcinoma.

The following examples and figures are intended to be illustrative but not to limit the invention. LEGENDS TO THE FIGURES :

- Figure 1 represents the aminoacid sequence of human ezrin before the maturation by deletion of the first aminoacid Met - Figure 2 shows the establishment of LLC-PK1 cell lines overexpressmg wild type ezrin (E1 , E2) or ezrin mutant tyr 353 to Phe (F1 , F2) The level of ezrin in cells overexpressmg wild type ezrin (E) and ezrin mutant (F) was compared to the level of endogenous ezrin in cells transfected with the vector alone (P) Figure 2a shows an immunodetection performed with anti-tag antibody Tagged ezrin is only detected in transfected cells

Figure 2b shows an immunodetection performed with the anti ezrin antibody

Figure 2c shows an immunolocaiization of ezrin in LLC-PK1 cells overproducing wild-type ezrin (top panel) or ezrin mutant (bottom panel)

- Figure 3 shows three cell lines (E cells overexpressmg wild type ezrin , F ceils overexpressmg ezrin mutant , P cells transfected with the vector alone), grown in a collagen matrix in presence of HGF F cells undergo apoptosis - Figure 4 shows three cell lines (E cells overexpressmg wild type ezrin , F cells overexpressmg ezrin mutant , P cells transfected with the vector alone), grown in Matπgel® gels Cells do not form tubules F cells do not undergo apoptosis

- Figure 5 shows three cell lines (E cells overexpressmg wild type ezrin , F cells overexpressmg ezrin mutant , P cells transfected with the vector alone), grown in poly HEMA coated dishes F cells undergo apoptosis Piknotic nuclei are observed in cell aggregates

- Figure 6 shows an estimation of the percentage of apoptotic cells grown on poly HEMA compared to cells grown on plastic dishes - Figure 7 shows DNA ladder showing apoptosis in F cells and also shows cells overexpressmg Bcl-2 (B) and F353 cells transfected with the vector alone (H), grown in a collagen matrix Bcl-2 can preserve the cells from apoptosis

- Figure 8 is a graph showing LLC-PK1 cell survival in function of the concentration of the PI3-K inhibitor, LY 294002

- Figure 9 shows an SDS-PAGE electrophoresis with the peptide biotin-RQIKIWFQNRRMKWKKLRLQDYEEKTK, or with the phosphorylated peptide bιotιn-RQIKIWFQNRRMKWKKLRLQD(pY)EEKTK Lane 0 is blank The PI3-K-p85 subunit specifically interacts with the phosphorylated peptide

EXAMPLES :

EXAMPLE 1 : Construction of ezrin mutated on tyrosine 353

Materials :

LLC-PK1 (CCL 101 , ATCC) cells were grown in DMEM growth medium (GIBCO BRL) supplemented with 10% fetal calf serum (FCS) and maintained at 37°C in 10% CO2

Rabbit polyclonal anti-ezπn antibody was raised against the entire ezrin produced in bacteria and was previously described (Algram et al _. 1993)

DNA constructs and transfection :

For generating the plasmid producing ezrin mutated on tyrosine 353 the following constructs were made To make the F353 mutant (wherein Tyr353 is replaced by Phe353), the two oligonucleotides

5' CGGAATTCCGGCTGCAGGACTTTGAGGAG 3' and

5' CGCGGATCCATTGTGGGTCC TCTTA 3' flanked with EcoRI and BamHI restriction sites respectively, were used to amplify the fragment (nucteotides 1125 to 1730) using the Ampli Taq polymerase (Perkin-Elmer

Corp , Norwalk, CT) This fragment was then subcloned into the Bluescπpt plasmid and checked by double-strand DNA sequencing using the T7 sequencing kit (Pharmacia FineChemicals, Piscataway, NJ) The fragment Pstl-Pstl corresponding to the sequence 1131 to 1197 and containing the mutated codon was inserted into the fragment Aval-Aval (nucleotides 1002- 1698) in the plasmid psp64. The fragment Aval-Aval of the full length ezrin cDNA in the plasmid psp64 was then replaced by the fragment Aval-Aval containing the mutated codon This mutant ezrin cDNA was then cloned in the expression vector pCB6 through the Hindlll and Xbal restriction sites

Exponentially growing LLC-PK1 cells were seeded 24 h before DNA transfer on 10-cm tissue culture dishes DNA transfer was performed following the procedure of Chen and Okayama, (1987) and cells transfected were selected by growing in media containing 0 7mg/ml Geneticme (G-418),

[Gibco BRL (Life Technologies) ref 11811-049] for 2-3 weeks

For each transfection, three/four clones overproducing the transfected protein (as detected by immunoblot and immunofluorescence analysis) were selected for further study

To generate the F353/ bcl-2 cell lines, the F353 LLC-PK1 cells (clone 7) were transfected with 20 μg of plasmid RSV-tk-hygromycin or plasmid RSV-tk- hygromycin- hbcl-2 by electroporation (240V and 950-μF) with the Gene Pulser II System (Bio-Rad, Hercules, Ca ) Transfected cells were selected with 02mg/ml of hygromycin B in presence of O 7 mg/ml G418 After 3 weeks of selection, individual colonies were isolated and expanded into cell lines

EXAMPLE 2 : Establishment of LLC-PK1 cell lines overexpressing wild type ezrin or Y353 ezrin

Materials

P5D4 mAb raised against the 11 -ammo acid carboxy terminus of the vesicular stomatitis virus glycoprotem G (VSV-G peptide), was previously described (Kreis, 1986) Results

Figure 2 shows the establishment of LLC-PK1 cell lines overexpressmg wild type ezrin (E1 , E2) or ezrin mutant tyr 353 to Phe (F1 , F2)

The level of ezrin in cells overexpressmg wild type ezrin (E) and ezrin mutant (F) was compared to the level of endogenous ezrin in cells transfected with the vector alone (P) Wild type and mutant ezrin were tagged with the VSV-G peptide at their carboxy-termmus The immunodetection performed with the anti ezrin antibody (Fig 2B) shows that the level of transfected ezrin is 5-10 fold higher than the endogenous ezrin (lane P) The localization of ezrin mutant is similar to that of wild type ezrin in LLC-PK1 cells (Fig 2C) There is not a striking morphological change when the cell lines are grown on plastic dishes

EXAMPLE 3 : Biological assays

Materials and methods For the tubulogenesis assay in three-dimensional collagen gels, the trypsmized cells were suspended at a final concentration of 1x10^ cells/ml in gelling solution, prepared as follows 1 part of DMEM 10x (GIBCO BRL), 1 part of NaHCO3 (37g/l), 1 part of FCS were mixed with 3 5 parts of a suspension of 3x10^ cells/ml and 3 5 parts of type I collagen at 5mg/ml (Collaborative Biomedical Products) at room temperature 100 μl of this mixture was seeded, in a microtiter plate, onto 100 μl of a first layer of collagen without cell suspension After 5 mm at 37°C, the gels were covered with cell culture medium +/- 100 U/ml HGF (dia-filtered, human fibroblast MRC5-condιtιoned medium (Naldini et al , 1995)) Photographs were taken with a light microscope (Leica) equipped with Nomarski interference optics To assess apoptosis, the cells in the collagen preparation were fixed with methanol for 5 mm and stained with HOECHST 33258 (10 μg/ml) The preparations were examined with a Leica microscope equipped with a UV-absorb g filter Condensed and fragmented nuclei were easily distinguishable from intact nuclei and percentage were calculated by counting

Growth of LLC-PK1 cell lines was tested in a growth factor reduced Matπgel®, a soluble basal membrane extract which do not contain collagen type I (Becton Dickinson Labware, Bedford, MA ) 1x10⁵ cells (1 v) were mixed with Matπgel® (5 v) and gelation occurred at 37°C

Results :

1. The survival of ezrin mutant is impaired in a collagen matrix (figure 3).

When the three cell lines P, E, F were grown in a collagen matrix in presence of HGF striking differences between the three cell lines were observed On the left panels, photographs were taken with a light microscope (Leica) equipped with Normarski interference optics On the right panels, nuclei are labelled with the intercalating dye, Hoechst 33258 P and E cells developped tubules with more ramifications when cells overexpressed wild type ezrin (E) However no tubulogenesis is observed with F ceils The few cells observed present fragmented nuclei typical of apoptosis (F) This suggested that ezrin mutant impairs the ability of cells to survive in a collagen matrix

2. Ezrin mutant survive in Matrigel® gels (figure 4).

The ability of the three cell lines to grow in a Matrigel® gel was tested All three cell lines were able to form cysts in the matrix and the F cell line did not undergo apoptosis as shown by analysis of the nuclei with the

Hoechst dye (left panels) This indicated that ezrin is in the survival pathway elicited by collagen type I matrix and not by Matrigel®

3. Cell survival mediated by ezrin is adhesion dependent (figures 5-6).

Growth of epithelial cells is anchorage dependent When the three cell lines were grown on an anti-adhesive substrate, the poly HEMA coated dishes, P and E cells escape apoptosis through aggregation and formation of cysts (figure 5) In contrast, a significant proportion of F cells underwent apoptosis within aggregates Apoptosis was estimated by two approaches First DNA ladder (figure 6 ) shows that a higher level of DNA fragmentation occurred in F cells compared to P or E cells Flow cytometπc analysis allowed to estimate the percentage of apoptotic cells grown on poly HEMA compared to cells grown on plastic dishes While the percentage of apoptotic cells is the same for all three clones grown on plastic dishes, the percentage of apoptotic cells is 2-3 times higher in F cells

4. Bcl-2 overexpression rescues F353 ezrin mutants from apoptosis (figure 7).

In order to confirm that apoptosis is due to a defect in signal transduction mediated by ezrin, cell lines overexpressmg Bcl-2 from F353 cells have been established The double transfected cell lines were tested for their ability to survive in a collagen matrix Fig 7 shows that cells overexpressmg Bcl- 2 survive in a collagen matrix (Fig 7B) while F353 cells transfected with the vector alone do not (Fig 7H) In addition, Bcl-2 transfected cells were able to form tubules, indicating that they did not lose their ability to interact with the collagen matrix

Altogether these data indicate that ezrin is involved in a specific pathway mediating cell survival

Furthermore since PI3-K (PI3-kιnase) has been shown to play a role in adhesion-dependent cell survival, it could be involved in this pathway

EXAMPLE 4 : Treatment of LLC-PK1 cells with the PI 3- kinase inhibitor, LY294002

Materials and methods :

The effect of LY294002 (Sigma ref L9908) was assessed on LLC-PK1 cells grown in type I collagen or Matrigel® matrices 10^ cells/ml were embedded in the matrices and cultured, as previously described, in presence of 100 U/ml HGF Cells were treated with LY294002 at increasing concentrations or with the vehicle DMSO After 24 h, cultures were permeabilized with several changes of methanol 100% for 30 mm at -20°C, and nuclei were stained with Hoechst 33258 (10 mg/ml in phosphate buffer saline) Condensed and intact nuclei were scored under microscope (Leica)

Results : Figure 8 shows that LLC-PK1 cell survival is impaired by the PI3-

K inhibitor, LY294002

LY294002 is a specific inhibitor of PI3-K When cells were grown in a collagen matrix in presence of various concentration of inhibitor, we observed a strong inhibition of cell survival at a concentration of LY294002 as low as 20 μM No apoptosis is observed at the same concentration when the cells are grown in a Matrigel® matrix This indicates that the cell survival signal elicited by the collagen matrix is PI3-K and ezrin dependent

EXAMPLE 5 : p85 interaction with phosphorylated peptides

Materials and methods :

The authors of the present invention have designed peptides that contain a biotin fused to the Antennapedia intemalization sequence (Derossi et al , 1994) in tandem with an eleven ammo-acid peptide corresponding to the ezrin ammo-acids 348-358 In one peptide, the tyrosine 353 was phosphorylated The peptide sequence is biotm-

RQIKIWFQNRRMKWKKLRLQDY(p)EEKTK

25 μl of Streptavidin Ultralink beads (Pierce, Rockford, IL, USA) were pre-mcubated with 300 μg of biotinylated peptides for 1 h at 4°C in buffer A (50 mM Hepes pH 7 4, 2 mM EDTA, 1 % Triton X-100 , 100 mM NaCI , 50 mM ammonium molybdate, 1 mM ZnCl2 ) 7 10⁶ LLC-PK1 cells grown on plastic dishes, were lysed with cold A buffer supplemented with a cocktail of protease inhibitors Extracts were clarified by centπfugation, 10 mm at 12000 g at 4°C The beads were incubated with the extracts for 1 h, washed 3 times with buffer A, and re-suspended in SDS loading buffer Samples were boiled and submitted to electrophoresis on SDS-PAGE

Results :

Figure 9 shows that Ezrin phosphorylated peptide (aa 348-358) interacts with the PI3-K p85 subunit The authors of the present invention made the hypothesis that interaction of the ezrin mutant with PI3-K was altered To test this hypothesis, an affinity column was performed with the ezrin peptides phosphorylated or not As shown in Fig 9 an interaction of PI3-K p85 subunit is only observed with the phosphorylated peptide

Altogether the above results indicate that

- Ezrin is involved in adhesion -dependent cell survival of epithelial cells

- Ezrin controls cell survival by activating the PI3-K whose downstream target, in this pathway, is the seπne/threonine kinase Akt

- This control is mediated by the interaction of the ezrin phosphorylated tyrosine residue 353 with the p85 subunit of the PI3-K

REFERENCES

Algrain, M , O Turunen, A Vaheπ, D Louvard, and M Arpm 1993 Ezrin contains cytoskeleton and membrane binding domains accounting for its proposed role as a membrane-cytoskeletal linker J Cell Biol 120 129- 139

Arpm M , M Algrain, and D Louvard 1994 Membrane-actiπ filament connections an increasing diversity of players related to band 4 1 Current Opinion Cell Biology, 6 136-141

Bardelli, A , F Mama, I Gout, M J Fry, M D Waterfield, P M Comoglio and C Ponzetto 1992 Autophosphorylation promotes complex formation of recombmant hepatocyte growth factor receptor with cytoplasmic effectors containing SH2 domains Oncogene 7 1973-1978

Bretscher A , 1983, Purification of an 80 000 dalton protein that is a component of the isolated microvillus cytoskeleton and its localization in nonmuscle cells J Cell Biol 97, 425-432

Chen, C , and H Okayama 1987 High-efficiency transformation of mammalian cells by plasmid DNA Mol Cell Biol 7 2745-2752

Crepaldi et al , 1997, The Journal of Cell Biology, 138(2) 423-434

Derossi, D , A H Joliot, G Chassamg, and A Prochiantz 1994 The third helix of the Antennapedia homeodomam translocates through biological membranes J Biol Chem 269 10444-10450

Kreig, J and Hunter, T , 1992, Identification of the two ma_jor epidermal growth factor-induced tyrosine phosphorylation sites in the microvillar core protein ezrin, J Biol-Chem , 267, 19258-65 Kreis, T E 1986 Micromjected antibodies against the cytoplasmic domain of vesicular stomatitis virus glycoprotem block its transport to the cell surface EMBO J 5 931-941

Naldmi, L , E Vigna, A Bardelli, A Follenzi, F Galimi, and P M Comoglio 1995 Biological activation of pro-HGF (hepatocyte growth factor) by urokmase is controlled by a stoichiometπc reaction J Biol Chem 270 603- 61 1

Naldmi, L , K M Weidner, E Vigna, G Gaudmo, A Bardelli, C Ponzetto, R P Narsimhan, G Hartmann, R Zarnegar, G K Michalopoulos, and et al 1991 Scatter factor and hepatocyte growth factor are indistinguishable ligands for the MET receptor EMBO J 10 2867-2878

Tsukita, S , S Yonemura, and S Tsukita 1997 ERM (ezπn/radixin/moesin) family from cytoskeleton to signal transduction Curr

Vaheπ, A , O Carpen, L Heiska, T S Helander, J Jaaskelamen,

P Majander-Nordenswan, M Sainio, T Timonen, and O Turunen 1997 The ezrin protein family membrane-cytoskeleton interactions and disease associations Curr Opm Cell Biol 9 659-666

Claims

1 A pharmaceutical composition containing an effective amount of ezrin mutated on tyrosine 353, or a functional fragment or derivative thereof, in association with a pharmaceutically acceptable carrier

2 A pharmaceutical composition containing an effective amount of DNA or RNA encoding eznn mutated on tyrosine 353, or encoding functional fragments or derivatives thereof

3 A pharmaceutical composition according to claim 2 wherein said DNA or RNA is in a naked form

4 A pharmaceutical composition according to any of claims 1 to 3 useful for the prevention and/or treatment of tumors

5 A pharmaceutical composition according to any of claims 1 to 4 useful for the prevention and/or treatment of metastasis

6 A method for the prevention and/or treatment of tumors, more particularly for the prevention and/or treatment of metastasis, comprising the administration to a patient in need of such treatment of an effective amount of a pharmaceutical composition according to any of claims 1 to 5